Icelandic Saga: Black Ice

We get our first real taste of ice on Iceland‘s southern coast at Solheimajökull, one of the glaciers photo-chronicled in James Balog’s Extreme Ice Survey. (The last part of the name is pronounced yokel, as in “local yokel,” and means “glacier” in Icelandic.) Quick Earth science lesson—grab some coffee: Glaciers work like conveyor belts or...

July 8, 2009

We get our first real taste of ice on Iceland‘s southern coast at Solheimajökull, one of the glaciers photo-chronicled in James Balog’s Extreme Ice Survey. (The last part of the name is pronounced yokel, as in “local yokel,” and means “glacier” in Icelandic.)

Quick Earth science lesson—grab some coffee:

Glaciers work like conveyor belts or escalators … sort of. Precipitation falls in the highlands as snow or rain, becomes ice, and compresses the ice below, which recrystallizes, gets more dense, and (once it piles high enough) begins to flow downward or outward.

As the ice in a glacier moves, it scours whatever it flows past, stripping soil, gouging bedrock, plucking boulders and cobbles and gravel, and grinding rocks together to produce sand and mud and a fine powder called loess. These make many of the rivers and lakes near glaciers look milky or muddy. Glacial ice also collects whatever falls on it—lots and lots of ash, for example, if you’re on an island such as this one that’s chock full of active volcanoes.

At a glacier’s margins, ice melts or is carried away as icebergs about as quickly as new ice arrives. The melting ice drops whatever rock and grit it’s carrying, some of which is flushed away in the meltwater, much of which piles up at the end of the glacier, over time forming large hills called “moraines.”

(Possibly-familiar example: Much of New York’s Long Island was once the moraine at the edge of an enormous Ice Age glacier.)

In the summer, more melting takes place, so glaciers often retreat up the valleys they’ve carved, then grow back during the winter. Lately, Iceland’s big glaciers and most others around the world have been retreating steadily up their valleys year after year, losing ground, and leaving large lagoons or gravel fields between their fringes and the moraines that define their recent boundaries.

Got it? Good!

We hiked across dusty volcanic gravel to reach Solheimajökull. While geologist Uly Horodyskyj scavenged the glacial debris for interesting rocks…

… Colleen measured the temperature and speed of winds coming off the ice…

… Ethan collected soil samples…

… and Will photographed the glacier.

Its margin was black with ash and rock, most of it carried within the ice for years but finally melted free.

Beneath the surface grime, however, the ice was clear, slick, and (who could’ve guessed?) ice-cold.

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